APPLYING ADDITION AND SUBTRACTION OF INTEGERS

About "Applying addition and subtraction of integers"

We can use what you know about adding and subtracting integers to solve real world problems.

Applying addition and subtraction of integers - Examples

Example 1 :

A seal is swimming in the ocean 5 feet below sea level. It dives down 12 feet to catch some fish. Then, the seal swims 8 feet up towards the surface with its catch. What is the seal’s final elevation relative to sea level ?

Solution :

Step 1 :

The seal starts at 5 feet below the surface, so its initial position is -5 ft.

Write an expression.

Starts - Dives down + Swims up

-5 - 12 + 8

Step 2 :

Add or subtract from left to right to find the value of the expression.

-5 - 12 + 8 = -17 + 8

= -9

The seal’s final elevation is 9 feet below sea level.

Example 2 :

Anna is in a cave 40 feet below the cave entrance. She descends 13 feet, then ascends 18 feet. Find her new position relative to the cave entrance.

Solution :

Step 1 :

Anna starts at 40 feet below cave entrance, so her initial position is -40 ft.

Write an expression.

Starts - Descends + Ascends

-40 - 13 + 18

Step 2 :

Add or subtract from left to right to find the value of the expression.

-40 - 13 + 18 = -53 + 18

= -35

Anna's new position is 35 feet below the cave entrance.

Example 3 :

Tomas works as an underwater photographer. He starts at a position that is 15 feet below sea level. He rises 9 feet, then descends 12 feet to take a photo of a coral reef. Write and evaluate an expression to find his position relative to sea level when he took the photo.

Solution :

Step 1 :

Tomas starts at 15 feet below sea level, so his initial position is -15 ft.

Write an expression.

Starts + Rises - Descends

-15 + 9 - 12

Step 2 :

Add or subtract from left to right to find the value of the expression.

-15 + 9 - 12 = -6 - 12

= -18

When Tomas takes photo, his position is 18 feet below the sea level.

After having gone through the stuff given above, we hope that the students would have understood "How to apply addition and subtraction of integers".

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